This application is an 371 of PCT/9399/00053 filed Feb. 12, 1999 and claims priority from United Kingdom Patent Applications GB 9802968.9, filed on Feb. 13, 1998, and GB 9827804.7, filed on Dec. 16, 1998.
The present invention relates to N-formyl hydroxylamine derivatives, to processes for their preparation, to pharmaceutical compositions containing them, and to the use of such compounds in medicine. In particular, the compounds are inhibitors of the proliferation of a range of rapidly dividing tumor cells, for example melanoma and/or lymphoma cells.
Anti-Proliferative Agents
There is a need in cancer therapy for therapeutic compounds which are inhibitors of the proliferation of tumor cells. One compound which is known to have such activity is 5-fluorouracil (5-FU).
Patent publication WO 98/11063 describes and claims the use of certain hydroxamic acid derivatives as inhibitors of tumor cell proliferation, and also describes and claims certain novel hydroxamic acids useful for that purpose.
Anti-Metastatic and Anti-Invasive Agents
Compounds which have the property of inhibiting the action of the metalloproteinase enzymes involved in connective tissue breakdown and remodelling, such as fibroblast collagenase (Type 1), PMN-collagenase, 72 kDa-gelatinase, 92 kDa-gelatinase, stromelysin, stromelysin-2 and PUMP-1 (known as xe2x80x9cmatrix metalloproteinasesxe2x80x9d, and herein referred to as MMPs) have been proposed and are being tested in the clinic for the treatment of solid tumors. Cancer cells are particularly adept at utilising the MMPs to achieve rapid remodelling of the extracellular matrix, thereby providing space for tumor expansion and permitting metastasis. MMP inhibitors should minimise these processes and thus slow or prevent cancer progression.
MMP inhibitors having an N-formyl hydroxylamine group as the zinc binding group have been proposed in the following publications, although very few examples of such compounds have been specifically made and described therein:
EP-B-0236872 (Roche)
WO 92/09563 (Glycomed)
WO 92/04735 (Syntex)
WO 95/19965 (Glycomed)
WO 95/22966 (Sanofi Winthrop)
WO 95/33709 (Roche)
WO 96/23791 (Syntex)
WO 96116027 (Syntex/Agouron)
WO 97/03783 (British Biotech)
WO 97/18207 (DuPont Merck)
WO 98/38179 (GlaxoWellcome)
WO 98/47863 (Labs Jaques Logeais)
This invention is based on the identification of a class of ester and thioester compounds containing an N-formyl hydroxylamine group, which inhibit proliferation of rapidly dividing cells. The ester and thioester compounds in question have certain structural similarities to known MMP inhibitors generically disclosed in the foregoing patent publications. However, most of those prior art publications are concerned with amides rather than esters or thioesters group. Despite the similarity of structure, it has been shown that compounds of the invention which have little or no MMP inhibitory activity are nonetheless potent inhibitors of such cell proliferation, implying a novel mechanism is at work. This antiproliferation property suggests a utility for the compounds of the present invention in the treatment of cancers.
The ester and thioester compounds useful according to the invention differ in structure from the hydroxamic acid derivatives disclosed as antiproliferative agents in WO 98/11063, mainly in that an N-formyl hydroxylamine group replaces the hydroxamic group.
Although the patent publications listed above predominantly disclose MMP inhibiting N-formyl hydroxylamine compounds having a terminal amide group, a few (WO 92/09563, WO 95/19965 and WO 95/22966) include within their generic disclosure compounds having a carboxylate ester group in place of the amide group. The carboxylate ester compounds with which this invention is concerned thus represent a selection of a notional subclass from the compounds proposed in the art as MMP inhibitors, for a specific and previously unrecognized pharmaceutical utility. The present inventors findings of inhibition of proliferation of rapidly dividing cells, including such tumor cells as lymphoma, leukemia, myeloma, adenocarcinoma, carcinoma, mesothelioma, teratocarcinoma, choriocarcinoma, small cell carcinoma, large cell carcinoma, melanoma, retinoblastoma, fibrosarcoma, leiomyosarcoma or endothelioma cells, by the esters and thioesters of the present invention, by a mechanism other than MMP inhibition, is not disclosed in or predictable from those earlier publications.
In its broadest aspect, the present invention provides a method for inhibiting proliferation of tumor cells in mammals, comprising administering to the mammal suffering such proliferation an amount of a compound of general formula (I) or a pharmaceutically acceptable salt hydrate or solvate thereof sufficient to inhibit such proliferation: 
wherein
R is hydrogen or (C1-C6)alkyl;
R1 is hydrogen;
(C1-C6)alkyl or fluoro-substituted alkyl;
(C2-C6)alkenyl;
phenyl or substituted phenyl;
phenyl(C1-C6)alkyl or substituted phenyl(C1-C6)alkyl;
phenyl(C2-C6)alkenyl or substituted phenyl(C2-C6)alkenyl
heterocyclyl or substituted heterocyclyl;
heterocyclyl(C1-C6)alkyl or substituted heterocyclyl(C1-C6)alkyl;
a group BSOnAxe2x80x94 wherein n is 0, 1 or 2 and B is hydrogen or a (C1-C6) alkyl, phenyl, substituted phenyl, heterocyclyl substituted heterocyclyl, (C1-C6)acyl, phenacyl or substituted phenacyl group, and A represents (C1-C6)alkylene;
amino(C1-C6)alkyl, (C1-C6)alkylamino(C1-C6)alkyl, di(C1-C6)alkyamino(C1-C6)alkyl, hydroxy(C1-C6)alkyl, mercapto(C1-C6)alkyl or carboxy(C1-C6)alkyl
wherein the amino-, hydroxy-, mercapto- or carboxyl-group are optionally protected or the carboxyl-group amidated;
lower alkyl substituted by carbamoyl, mono(lower alkyl)carbamoyl, di(lower alkyl)carbamoyl, di(lower alkyl)amino, or carboxy-lower alkanoylamino;
a cycloalkyl, cycloalkenyl, cycloalkyl(C1-C6alkyl)xe2x80x94, cycloalkenyl(C1-C6alkyl)xe2x80x94 or non-aromatic heterocyclic ring containing up to 3 heteroatoms, any of which may be (i) substituted by one or more substituents selected from C1-C6 alkyl, C2-C6 alkenyl, halo, cyano(xe2x80x94CN), xe2x80x94CO2H, xe2x80x94CO2R, xe2x80x94CONH2, xe2x80x94CONHR, xe2x80x94CON(R)2, xe2x80x94OH, xe2x80x94OR, oxoxe2x80x94, xe2x80x94SH, xe2x80x94SR, xe2x80x94NHCOR, and xe2x80x94NHCO2R wherein R is C1-C6 alkyl or benzyl and/or (ii) fused to a cycloalkyl or heterocyclic ring;
R2 is a C1-C12 alkyl,
C2-C12 alkenyl,
C2-C12 alkynyl,
phenyl(C1-C6 alkyl)xe2x80x94,
heteroaryl(C1-C6 alkyl)xe2x80x94,
phenyl(C2-C6 alkenyl)xe2x80x94,
heteroaryl(C2-C6 alkenyl)xe2x80x94,
phenyl(C2-C6 alkynyl)xe2x80x94,
heteroaryl(C2-C6 alkynyl)xe2x80x94,
cycloalkyl(C1-C6 alkyl)xe2x80x94,
cycloalkyl(C2-C6 alkenyl)xe2x80x94,
cycloalkyl(C2-C6 alkynyl)xe2x80x94,
cycloalkenyl(C1-C6 alkyl)xe2x80x94,
cycloalkenyl(C2-C6 alkenyl)xe2x80x94,
cycloalkenyl(C2-C6 alkynyl)xe2x80x94,
phenyl(C1-C6 alkyl)O(C1-C6 alkyl)xe2x80x94, or
heteroaryl(C1-C6 alkyl)O(C1-C6 alkyl)xe2x80x94 group,
any one of which may be optionally substituted by
C1-C6 alkyl,
C1-C6 alkoxy,
halo,
cyano(xe2x80x94CN),
phenyl or heteroaryl, or
phenyl or heteroaryl substituted by
C1-C6 alkyl,
C1-C6 alkoxy,
halo, or
cyano(xe2x80x94CN);
R3 is the characterising group of a natural or non-natural a amino acid in which any functional groups may be protected; and
R4 is an ester or thioester group,
or a pharmaceutically acceptable salt, hydrate or solvate thereof.
In another broad aspect of the invention, there is provided the use of a compound of formula (I) as defined in the immediately preceding paragraph, in the preparation of a pharmaceutical composition for inhibiting proliferation of tumor cells in mammals.
The present invention also provides novel compounds of general formula (I) above wherein R, R1, R2, R3 and R4 are as defined above with reference to formula (I), and pharmaceutically acceptable salts, hydrates or solvates thereof, PROVIDED THAT (i) R3 is not a bicyclicarylmethyl group or (ii) R2 is not a phenyl(C1-C6 alkyl)O(C1-C6 alkyl)xe2x80x94, or heteroaryl(C1-C6 alkyl)O(C1-C6 alkyl)xe2x80x94 group, or a C1-C12 alkyl, C2-C12 alkenyl, or C2-C12 alkynyl group substituted by a C1-C6 alkoxy group.
One particular sub-group of the novel esters and thioesters of the invention consists of compounds of formula (I) above, wherein:
R, R1 and R4 are as defined above with reference to formula (I)
R2 is C1-C12 alkyl, C2-C12 alkenyl, C2-C12 alkynyl,
phenyl(C1-C6 alkyl)xe2x80x94, cycloalkyl(C1-C6 alkyl)xe2x80x94, or heteroaryl(C1-C6 alkyl)xe2x80x94,
biphenyl(C1-C6 alkyl)xe2x80x94, phenylheteroaryl(C1-C6 alkyl)xe2x80x94, heteroarylphenyl(C1-C6 alkyl)xe2x80x94,
biphenyl(C2-C6 alkenyl)xe2x80x94, phenylheteroaryl(C2-C6 alkenyl)xe2x80x94, heteroarylphenyl(C2-C6 alkenyl)xe2x80x94,
phenyl(C2-C6 alkynyl)xe2x80x94, heteroaryl(C2-C6 alkynyl)xe2x80x94, biphenyl(C2-C6 alkynyl)xe2x80x94, phenylheteroaryl(C2-C6 alkynyl)xe2x80x94, heteroarylphenyl(C2-C6 alkynyl)xe2x80x94,
any one of which may be optionally substituted on a ring carbon atom by C1-C6 alkyl, C1-C6 alkoxy, halo, or cyano(xe2x80x94CN); and
R3 is C1-C6 alkyl, optionally substituted benzyl, optionally substituted phenyl, optionally substituted heteroaryl; or
the characterising group of a natural xcex1 amino acid, in which any functional group may be protected, any amino group may be acylated, any carboxyl group present may be amidated, and any hydroxyl group etherified; or
a heterocyclic(C1-C6)alkyl group, optionally substituted in the heterocyclic ring;
and pharmaceutically acceptable salts, hydrates or solvates thereof.
As used herein the term xe2x80x9c(C1-C6)alkylxe2x80x9d or xe2x80x9clower alkylxe2x80x9d means a straight or branched chain alkyl moiety having from 1 to 6 carbon atoms, including for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, n-pentyl and n-hexyl.
The term xe2x80x9c(C2-C6)alkenylxe2x80x9d means a straight or branched chain alkenyl moiety having from 2 to 6 carbon atoms having at least one double bond of either E or Z stereochemistry where applicable. This term would include, for example, vinyl, allyl, 1- and 2-butenyl and 2-methyl-2-propenyl.
The term xe2x80x9cC2-C6 alkynylxe2x80x9d refers to straight chain or branched chain hydrocarbon groups having from two to six carbon atoms and having in addition one triple bond. This term would include for example, ethynyl, 1-propynyl, 1- and 2-butynyl, 2-methyl-2-propynyl, 2-pentynyl, 3-pentynyl, 4-pentynyl, 2-hexynyl, 3-hexynyl, 4-hexynyl and 5-hexynyl.
The term xe2x80x9ccycloalkylxe2x80x9d means a saturated alicyclic moiety having from 3-8 carbon atoms and includes, for example, cyclohexyl, cyclooctyl, cycloheptyl, cyclopentyl, cyclobutyl and cyclopropyl.
The term xe2x80x9ccycloalkenylxe2x80x9d means an unsaturated alicyclic moiety having from 4-8 carbon atoms and includes, for example, cyclohexenyl, cyclooctenyl, cycloheptenyl, cyclopentenyl, and cyclobutenyl. In the case of cycloalkenyl rings of from 5-8 carbon atoms, the ring may contain more than one double bond.
The term xe2x80x9carylxe2x80x9d means an unsaturated aromatic carbocyclic group which is moncyclic (eg phenyl), polycyclic (eg naphthyl) or consists of two covalently linked unsaturated aromatic carbocyclic groups (eg biphenyl).
The unqualified term xe2x80x9cheterocyclylxe2x80x9d or xe2x80x9cheterocyclicxe2x80x9d means (i) a 5-7 membered heterocyclic ring containing one or more heteroatoms selected from S, N and O, and optionally fused to a benzene ring, including for example, pyrrolyl, furyl, thienyl, piperidinyl, imidazolyl, oxazolyl, thiazolyl, thiadiazolyl, pyrazolyl, pyridinyl, pyrrolidinyl, pyrimidinyl, morpholinyl, piperazinyl, indolyl, benzimidazolyl, maleimido, succinimido, phthalimido, 1,2-dimethyl-3,5-dioxo-1,2,4-triazolidin-4-yl, 3,4,4-trimethyl-2,5-dioxo-1-imidazolidinyl, 2-methyl-3,5-dioxo-1,2,4-oxadiazol-4-yl, 3-methyl-2,4,5-trioxo-1-imidazolidinyl, 2,5-dioxo-3-phenyl-1-imidazolidinyl, 2-oxo-1-pyrrolidinyl, 2,5-dioxo-1-pyrrolidinyl or 2,6-dioxopiperidinyl, or (ii) a naphththalimido (ie 1,3-dihydro-1,3-dioxo-2H-benz[f]isoindol-2-yl), 1,3-dihydro-1-oxo-2H-benz[f]isoindol-2-yl, 1,3-dihydro-1,3-dioxo-2H-pyrrolo[3,4-b]quinolin-2-yl, or 2,3-dihydro-1,3-dioxo-1H-benz[d,e]isoquinolin-2-yl group.
The term xe2x80x9cheteroarylxe2x80x9d means a 5-7 membered substituted or unsubstituted aromatic heterocycle containing one or more heteroatoms. Illustrative of such rings are thienyl, furyl, pyrrolyl, imidazolyl, thiazolyl, pyrazolyl, isoxazolyl, isothiazolyl, trizolyl, thiadiazolyl, oxadiazolyl, pyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl and triazinyl.
The term xe2x80x9cesterxe2x80x9d or xe2x80x9cesterified carboxyl groupxe2x80x9d means a group R9O(Cxe2x95x90O)xe2x80x94 in which R9 is the group characterising the ester, notionally derived from the alcohol R9OH.
The term xe2x80x9cthioesterxe2x80x9d means a group R9S(Cxe2x95x90O)xe2x80x94 or R9S(Cxe2x95x90S)xe2x80x94 or R9O(Cxe2x95x90S)xe2x80x94 in which R9 is the group characterising the thioester, notionally derived from the alcohol R9OH or the thioalcohol R9SH.
The term xe2x80x9cbicyclicarylmethylxe2x80x9d means (i) a methyl group substituted by a monocyclic aryl or heteroaryl group which in turn is substituted by a monocyclic aryl or heteroaryl group, or (ii) a methyl group substituted by a monocyclic aryl or heteroaryl group to which is fused a second monocyclic aryl or heteroaryl group; and includes both unsubstituted and substituted bicyclicarylmethyl. Examples of such bicyclicarylmethyl groups include naphthyl, indolyl, quinolyl and isoquinolyl.
Unless otherwise specified in the context in which it occurs, the term xe2x80x9csubstitutedxe2x80x9d as applied to any moiety herein means substituted with up to four substituents, each of which independently may be (C1-C6)alkyl, (C1-C6)alkoxy, hydroxy, mercapto, (C1-C6)alkylthio, amino, halo (including fluoro, chloro, bromo and iodo), nitro, trifluoromethyl, xe2x80x94COOH, xe2x80x94CONH2, xe2x80x94CN, xe2x80x94COORA, xe2x80x94CONHRA or xe2x80x94CONHRARA wherein RA is a (C1-C6)alkyl group or the residue of a natural alpha-amino acid.
The term xe2x80x9cside chain of a natural or non-natural alpha-amino acidxe2x80x9d means the group R1 in a natural or non-natural amino acid of formula NH2xe2x80x94CH(R1)xe2x80x94COOH.
Examples of side chains of natural alpha amino acids include those of alanine, arginine, asparagine, aspartic acid, cysteine, cystine, glutamic acid, histidine, 5-hydroxylysine, 4-hydroxyproline, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, valine, xcex1-aminoadipic acid, xcex1-amino-n-butyric acid, 3,4-dihydroxyphenylalanine, homoserine, xcex1-methylserine, ornithine, pipecolic acid, and thyroxine.
Natural alpha-amino acids which contain functional substituents, for example amino, carboxyl, hydroxy, mercapto, guanidyl, imidazolyl, or indolyl groups in their characteristic side chains include arginine, lysine, glutamic acid, aspartic acid, tryptophan, histidine, serine, threonine, tyrosine, and cysteine. When R3 in the compounds of the invention is one of those side chains, the functional substituent may optionally be protected.
The term xe2x80x9cprotectedxe2x80x9d when used in relation to a functional substituent in a side chain of a natural alpha-amino acid means a derivative of such a substituent which is substantially non-functional. For example, carboxyl groups may be esterified (for example as a C1-C6 alkyl ester), amino groups may be converted to amides (for example as a NHCOC1-C6 alkyl amide) or carbamates (for example as an NHC(xe2x95x90O)OC1-C6 alkyl or NHC(xe2x95x90O)OCH2Ph carbamate), hydroxyl groups may be converted to ethers (for example an OC1-C6 alkyl or a O(C1-C6 alkyl)phenyl ether) or esters (for example a OC(xe2x95x90O)C1-C6 alkyl ester) and thiol groups may be converted to thioethers (for example a tert-butyl or benzyl thioether) or thioesters (for example a SC(xe2x95x90O)C1-C6 alkyl thioester).
Examples of side chains of non-natural alpha amino acids include those referred to below in the discussion of suitable R3 groups for use in compounds of the present invention.
Salts of the compounds of the invention include physiologically acceptable acid addition salts for example hydrochlorides, hydrobromides, sulfates, methane sulfonates, p-toluenesulfonates, phosphates, acetates, citrates, succinates, lactates, tartrates, fumarates and maleates. Salts may also be formed with bases, for example sodium, potassium, magnesium, and calcium salts.
There are several chiral centres in the compounds according to the invention because of the presence of asymmetric carbon atoms. The presence of several asymmetric carbon atoms gives rise to a number of diastereomers with R or S stereochemistry at each chiral centre. All such diastereomers and mixtures thereof are included within the scope of the invention.
As previously stated, the compounds with which the present invention is concerned are principally distinguished from the compounds disclosed in WO 98/11063 publications listed above by the N-formylhydroxylamine group, and from the other prior patent publications listed above by the presence of the ester or thioester group R4. Accordingly the groups R, R1, R2, and R3, may include those which have been disclosed in the corresponding positions of compounds disclosed in WO 98/11063 and any of those other prior art patent publications. Without limiting the generality of the foregoing, examples of substituents R to R4 are given below:
The Group R1 
R1 may be, for example,
hydrogen, methyl, 3,3,3-trifluoropropyl, n-propyl, n-butyl, isobutyl, allyl, cyclopentylmethyl, phenylpropyl, cyclopropylmethyl, phenylprop-2-enyl, thienylsulfanylmethyl, thienylsulfinylmethyl, or thienylsulfonylmethyl; or C1-C4 alkyl, eg methyl, ethyl n-propyl or n-butyl, substituted by a phthalimido, 1,2-dimethyl-3,5-dioxo-1,2,4-triazolidin-4-yl, 3-methyl-2,5-dioxo-1-imidazolidinyl, 3,4,4-trimethyl-2,5-dioxo-1-imidazolidinyl, 2-methyl-3,5-dioxo-1,2,4-oxadiazol-4-yl, 3-methyl-2,4,5-trioxo-1-imidazolidinyl, 2,5-dioxo-3-phenyl-1-imidazolidinyl, 2-oxo-1-pyrrolidinyl, 2,5-dioxo-1-pyrrolidinyl or 2,6-dioxopiperidinyl, 5,5-dimethyl-2,4-dioxo-3-oxazolidinyl, hexahydro-1,3-dioxopyrazolo[1,2,a][1,2,4]-triazol-2-yl, or a naphththalimido (ie 1,3-dihydro-1,3-dioxo-2H-benz[f]isoindol-2-yl), 1,3-dihydro-1-oxo-2H-benz[f]isoindol-2-yl, 1,3-dihydro-1,3-dioxo-2H-pyrrolo[3,4-b]quinolin-2-yl, or 2,3-dihydro-1,3-dioxo-1H-benz[d,e]isoquinolin-2-yl group; or
cyclohexyl, cyclooctyl, cycloheptyl, cyclopentyl, cyclobutyl, cyclopropyl, tetrahydropyranyl or morpholinyl.
Presently preferred R1 groups include hydrogen, cyclopropylmethyl, n-propyl, trifluoropropyl and allyl.
The Group R2 
R2 may for example be
C1-C12 alkyl, C3-C6 alkenyl or C3-C6 alkynyl;
cycloalkyl(C1-C6 alkyl)xe2x80x94;
phenyl(C1-C6 alkyl)xe2x80x94, phenyl(C3-C6 alkenyl)xe2x80x94 or phenyl(C3-C6 alkynyl)xe2x80x94 optionally substituted in the phenyl ring;
heteroaryl(C1-C6 alkyl)xe2x80x94, heteroaryl(C3-C6 alkenyl)xe2x80x94 or heteroaryl(C3-C6 alkynyl)xe2x80x94 optionally substituted in the heteroaryl ring;
4-phenylphenyl(C1-C6 alkyl)xe2x80x94, 4-phenylphenyl(C3-C6 alkenyl)xe2x80x94, 4-phenylphenyl(C3-C6 alkynyl)xe2x80x94, 4-heteroarylphenyl(C1-C6 alkyl)xe2x80x94, 4-heteroarylphenyl(C3-C6 alkenyl)xe2x80x94,
4-heteroarylphenyl(C3-C6 alkynyl)xe2x80x94, optionally substituted in the terminal phenyl or heteroaryl ring;
phenoxy(C1-C6 alkyl)xe2x80x94 or heteroaryloxy(C1-C6 alkyl)xe2x80x94 optionally substituted in the phenyl or heteroaryl ring;
Specific examples of such groups include methyl, ethyl, n- or iso-propyl, n-, iso- or tert-butyl, n-pentyl, n-hexyl, n-heptyl, n-nonyl, n-decyl, benzyl, cyclopentylmethyl, cyclopropylmethyl, prop-2-yn-1-yl, 3-phenylprop-2-yn-1-yl, 3-(2-chlorophenyl)prop-2-yn-1-yl, benzyl phenylpropyl, 4-chlorophenylpropyl, 4-methylphenylpropyl, 4-methoxyphenylpropyl, phenoxybutyl, 3-(4-pyridylphenyl)propyl-, 3-(4-(4-pyridyl)phenyl)prop-2-yn-1-yl, 3-(4-phenylphenyl)propyl-, 3-(4-phenyl)phenyl)prop-2-yn-1-yl and 3-[(4-chlorophenyl)phenyl]propyl-.
Presently preferred R2 groups include benzyl, n-butyl, iso-butyl, n-hexyl, cyclopentylmethyl, cyclopropylmethyl, and 3-(2-chlorophenyl)prop-2-yn-1-yl.
The Group R3 
R3 may for example be C1-C6 alkyl, phenyl, 2-, 3-, or 4-pyridyl, 2- or 3-thienyl, 2-, 3-, or 4-hydroxyphenyl, 2-, 3-, or 4-methoxyphenyl, 2-, 3-, or 4-pyridylmethyl, benzyl, 2-, 3-, or 4-hydroxybenzyl, 2-, 3-, or 4-benzyloxybenzyl, 2-, 3-, or 4-C1-C6 alkoxybenzyl, or benzyloxy(C1-C6alkyl)xe2x80x94; or
the characterising group of a natural xcex1-amino acid, in which any functional group may be protected, any amino group may be acylated and any carboxyl group present may be amidated; or a group -[Alk]nR6 where Alk is a (C1-C6)alkyl or (C2-C6)alkenyl group optionally interrupted by one or more xe2x80x94Oxe2x80x94, or xe2x80x94Sxe2x80x94 atoms or xe2x80x94N(R7)xe2x80x94 groups [where R7 is a hydrogen atom or a (C1-C6)alkyl group], n is 0 or 1, and R6 is an optionally substituted cycloalkyl or cycloalkenyl group; or a benzyl group substituted in the phenyl ring by a group of formula xe2x80x94OCH2COR8 where R8 is hydroxyl, amino, (C1-C6)alkoxy, phenyl(C1-C6)alkoxy, (C1-C6)alkylamino, di((C1-C6)alkyl)amino, phenyl(C1-C6)alkylamino, the residue of an amino acid or acid halide, ester or amide derivative thereof, said residue being linked via an amide bond, said amino acid being selected from glycine, xcex1 or xcex2 alanine, valine, leucine, isoleucine, phenylalanine, tyrosine, tryptophan, serine, threonine, cysteine, methionine, asparagine, glutamine, lysine, histidine, arginine, glutamic acid, and aspartic acid; or
a heterocyclic(C1-C6)alkyl group, either being unsubstituted or mono- or di-substituted in the heterocyclic ring with halo, nitro, carboxy, (C1-C6)alkoxy, cyano, (C1-C6)alkanoyl, trifluoromethyl(C1-C6)alkyl, hydroxy, formyl, amino, (C1-C6)alkylamino, di-(C1-C6)alkylamino, mercapto, (C1-C6)alkylthio, hydroxy(C1-C6)alkyl, mercapto(C1-C6)alkyl or (C1-C6)alkylphenylmethyl; or
a group xe2x80x94CRaRbRc in which:
each of Ra, Rb and Rc is independently hydrogen, (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, phenyl(C1-C6)alkyl, (C3-C8)cycloalkyl; or
Rc is hydrogen and Ra and Rb are independently phenyl or heteroaryl such as pyridyl; or
Rc is hydrogen, (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, phenyl(C1-C6)alkyl, or (C3-C8)cycloalkyl, and Ra and Rb together with the carbon atom to which they are attached form a 3 to 8 membered cycloalkyl or a 5- to 6-membered heterocyclic ring; or
Ra, Rb and Rc together with the carbon atom to which they are attached form a tricyclic ring (for example adamantyl); or
Ra and Rb are each independently (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, phenyl(C1-C6)alkyl, or a group as defined for Rc below other than hydrogen, or Ra and Rb together with the carbon atom to which they are attached form a cycloalkyl or heterocyclic ring, and Rc is hydrogen, xe2x80x94OH, xe2x80x94SH, halogen, xe2x80x94CN, xe2x80x94CO2H, (C1-C4)perfluoroalkyl, xe2x80x94CH2OH, xe2x80x94CO2(C1-C6)alkyl, xe2x80x94O(C1-C6)alkyl, xe2x80x94O(C2-C6)alkenyl, xe2x80x94S(C1-C6)alkyl, xe2x80x94SO(C1-C6)alkyl, xe2x80x94SO2(C1-C6)alkyl, xe2x80x94S(C2-C6)alkenyl, xe2x80x94SO(C2-C6)alkenyl, xe2x80x94SO2(C2-C6)alkenyl or a group xe2x80x94Qxe2x80x94W wherein Q represents a bond or xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94SOxe2x80x94 or xe2x80x94SO2xe2x80x94 and W represents a phenyl, phenylalkyl, (C3-C8)cycloalkyl, (C3-C8)cycloalkylalkyl, (C4-C8)cycloalkenyl, (C4-C8)cycloalkenylalkyl, heteroaryl or heteroarylalkyl group, which group W may optionally be substituted by one or more substituents independently selected from, hydroxyl, halogen, xe2x80x94CN, xe2x80x94CO2H, xe2x80x94CO2(C1-C6)alkyl, xe2x80x94CONH2, xe2x80x94CONH(C1-C6)alkyl, xe2x80x94CONH(C1-C6alkyl)2, xe2x80x94CHO, xe2x80x94CH2OH, (C1-C4)perfluoroalkyl, xe2x80x94O(C1-C6)alkyl, xe2x80x94S(C1-C6)alkyl, xe2x80x94SO(C1-C6)alkyl, xe2x80x94SO2(C1-C6)alkyl, xe2x80x94NO2, xe2x80x94NH2, xe2x80x94NH(C1-C6)alkyl, xe2x80x94N((C1-C6)alkyl)2, xe2x80x94NHCO(C1-C6)alkyl, (C1-C6)alkyl, (C2-C6)alkenyl, (C2-C6)alkynyl, (C3-C8)cycloalkyl, (C4-C8)cycloalkenyl, phenyl or benzyl.
Examples of particular R3 groups include benzyl, phenyl, cyclopentylmethyl, cyclohexylmethyl, pyridin-3-ylmethyl, 2- or 3-thienyl, 3-, or 4-methoxyphenyl, tert-butoxymethyl, iso-propyl, iso-butyl, sec-butyl, tert-butyl, 1-benzylthio-1-methylethyl, 1-methylthio-1-methylethyl, and 1-mercapto-1-methylethyl.
Presently preferred R3 groups include phenyl, 3-, or 4-methoxyphenyl, benzyl, tert-butoxymethyl, iso-propyl and iso-butyl.
The Group R4 
Examples of particular ester and thioester groups R4 groups include those of formula xe2x80x94(Cxe2x95x90O)OR9, xe2x80x94(Cxe2x95x90O)SR9, xe2x80x94(Cxe2x95x90S)SR9, and xe2x80x94(Cxe2x95x90S)OR9 wherein R9 is (C1-C6)alkyl, (C2-C6)alkenyl, cycloalkyl, cycloalkyl(C1-C6)alkyl-, phenyl, heterocyclyl, phenyl(C1-C6)alkyl-, heterocyclyl(C1-C6)alkyl-, (C1-C6)alkoxy(C1-C6)alkyl-, (C1-C6)alkoxy(C1-C6)alkoxy(C1-C6)alkyl-, any of which may be substituted on a ring or non-ring carbon atom or on a ring heteroatom, if present. Examples of such R9 groups include methyl, ethyl, n-and iso-propyl, n-, sec- and tert-butyl, 1-ethyl-prop-1-yl, 1-methyl-prop-1-yl, 1-methyl-but-1-yl, cyclobutanyl, cyclopentyl, cyclohexyl, cyclopentylmethyl, allyl, phenyl, benzyl, 2-, 3- and 4-pyridylmethyl, N-methylpiperidin-4-yl, 1-methylcyclopent-1-yl, adamantyl, tetrahydrofuran-3-yl, tetrahydropyranyl and methoxyethyl.
Presently preferred are compounds of formula (IB) wherein R4 is a carboxylate ester of formula xe2x80x94(Cxe2x95x90O)OR9, wherein R9 g is benzyl, cyclopentyl, or isopropyl.
The Group R
Presently preferred R groups are hydrogen and methyl.
Specific examples of compounds of the invention include those prepared according to the Examples below, and salts, hydrates and solvates thereof.
Compounds of the invention may be prepared by deprotecting an O-protected N-formyl-N-hydroxyamino compound of formula (II): 
in which R1, R2, R3 and R4 are as defined in general formula (I) and R25 is a hydroxy protecting group removable to leave a hydroxy group by hydrogenolysis or hydrolysis. Benzyl is a preferred R25 group for removal by hydrogenolysis, and tetrahydropyranyl is a preferred group for removal by acid hydrolysis.
Compounds of formula (II) may be prepared by causing an acid of formula (III) or an activated derivative thereof to react with an amine of formula (IV) 
wherein R, R1, R2, R3 and R4 are as defined in general formula (I) except that any substituents in R1, R2, R3 and R4 which are potentially reactive in the coupling reaction may themselves be protected from such reaction, and R25 is as defined in relation to formula (II) above, and optionally removing protecting groups from R1, R2, R3 and R4.
Compounds of formula (III) may be prepared by N-formylation, for example using acetic anhydride and formic acid, or 1-formylbenzotriazole, of compounds of formula (V) 
wherein R1, R2 and R25 are as defined in relation to formula (II) and X is either a chiral auxiliary or an OR26 group wherein R26 is hydrogen or a hydroxy protecting group. In the case where X is an OR26 group or a chiral auxiliary the hydroxy protecting group or auxiliary is removed after the formylation step to provide the compound of formula (III). Suitable chiral auxiliaries include substituted oxazolidinones which may be removed by hydrolysis in the presence of base.
In an alternative procedure compounds of general formula (II) may be prepared by N-formylation, for example using acetic anhydride and formic acid, or 1-formylbenzotriazole, of compounds of formula (VI) 
wherein R, R1, R2, R3, R4, and R25 are as defined in relation to formula (II).
Compounds of general formula (V) and (VI) may be prepared by reduction of an oxime of general formula (VII) or (VIII) respectively: 
wherein R, R1, R2, R3, R4, and R25 are as defined above, and X is either an OR26 group as defined above or a chiral auxiliary. Reducing agents include certain metal hydrides (eg sodium cyanoborohydride in acetic acid, triethylsilane or borane/pyridine) and hydrogen in the presence of a suitable catalyst. Following the reduction when the group X is a chiral auxiliary it may be optionally converted to a OR26 group.
Compounds of general formula (VII) and (VIII) can be prepared by reaction of a xcex2-keto carbonyl compound of general formula (VIIA) or (VIIIA) 
wherein X, R, R1, R2, R3, R4, and R25 are as defined above, with an O-protected hydroxylamine.
xcex2-keto carbonyl compounds (VIIIA) may be prepared by reaction of a xcex2-keto carbonyl (VIIA) wherein R and R2 are as defined on relation to formula (II) and X is a hydroxy group or an activated derivative thereof, with an amine of formula (IV) as defined above. Any substituents in R, R1, R2, R3, and R4 which are potentially reactive in the coupling reaction may be protected during the reaction and subsequently removed.
xcex2-keto carbonyl compounds (VIIA) may be prepared by formylation or acylation of a carbonyl compound of general formula (VIIB): 
wherein R2 is as defined above and X is either a chiral auxiliary or an OR26 group wherein R26 is a hydroxy protecting group with a compound of general formula (IX) 
wherein R1 is as defined above and Z is a leaving group such as halogen or alkoxy, in the presence of base. Chiral enolates of this type have been described by Evans (J. Am. Chem. Soc., 104, 1737, (1982)).
Another method for the preparation of a compound of general formula (V) wherein R25 is a hydroxyl protecting group is by Michael addition of a hydroxylamine derivative to an xcex1,xcex2-unsaturated carbonyl compounds of general formula (X) 
wherein R1, R2, and X are as defined above. The xcex1,xcex2-unsaturated carbonyl compounds (X) may be prepared by standard methods.
Compounds of formula (V) wherein X is an an OR26 wherein R26 is hydrogengroup may alternatively be prepared by treating a compound of formula (XI) with aqueous sodium hydroxide. 
wherein R1, R2 and R25 are as defined above.
Compounds of formula (XI) may be prepared from alcohols of formula (XII) wherein R1, R2 and R25 are as defined above. by activation of the alcohol, for example with methane sulfonyl chloride, in the presence of triethylamine. The cyclisation may then be accomplished in the presence of a suitable base, for example potassium carbonate. 
Compounds of formula (XII) may be prepared by causing an acid of formula (XIII) or an activated derivative thereof to react with an 0-protected hydroxylamine derivative (XIV). 
wherein R1, R2 and R25 are as defined above.
Compounds of formula (XIII) may be prepared by the deprotection of an ester of formula (XV) 
wherein R1 and R2 are as defined above and R27 is a hydroxy protecting group
Compounds of formula (XV) may be prepared by the alkylation of compounds of formula (XVI). The reaction may be performed by deprotonation with a strong base, such as lithium hexamethyl disilazide followed by treatment with an alkylating agent of formula (XVII). 
wherein R1, R2 and R27 are as defined above and Z is a leaving group such as halo, mesylate, tosylate, or triflate.
Compounds of formula (XVI) may be prepared by the reduction of a ketone of formula (XVIII). This may be performed in a highly stereoselective fashion using a chiral catalyst, such as [RuC12(BINAP)]2.NEt3 under an atmosphere of hydrogen gas. 
wherein R1 and R27 are as defined above.
As mentioned above, compounds of formula (I) above, and those of formula (I) excluded by the provisos in the definition of formula (I) above, are useful in human or veterinary medicine since they are active as inhibitors of the proliferation of cancer cells. The utility of the invention therefore lies in the treatment of cancers, such as those caused by over-proliferation of lymphoma, leukemia, myeloma, adenocarcinoma, carcinoma, mesothelioma, teratocarcinoma, choriocarcinoma, small cell carcinoma, large cell carcinoma, melanoma, retinoblastoma, fibrosarcoma, leiomyosarcoma, glioblastoma or endothelioma cells. It will be understood that different compounds (I) will have differing potencies as proliferation inhibitors depending on the the type of cancer being treated. The activity of any particular compound (I) in inhibiting proliferation of any particular cell type may be routinely determined by standard methods, for example analagous to those described in the Biological Example herein. From the fact that compounds (I) which are poorly active as inhibitors of MMPs are nonetheless active in inhibiting proliferation of cancer cells, it is inferred that their utility in treating cancers is different from or supplementary to the utility of effective MMP inhibitors in the treatment of cancers.
In a further aspect of the invention there is provided a pharmaceutical or veterinary composition comprising a compound of the invention as defined by reference to formula (IB) above, together with a pharmaceutically or veterinarily acceptable excipient or carrier. One or more compounds of the invention may be present in the composition together with one or more excipient or carrier.
The compounds with which the invention is concerned may be prepared for administration by any route consistent with their pharmacokinetic properties.
Orally administrable compositions may be in the form of tablets, capsules, powders, granules, lozenges, liquid or gel preparations, such as oral, topical, or sterile parenteral solutions or suspensions. Tablets and capsules for oral administration may be in unit dose presentation form, and may contain conventional excipients such as binding agents, for example syrup, acacia, gelatin, sorbitol, tragacanth, or polyvinyl-pyrrolidone; fillers for example lactose, sugar, maize-starch, calcium phosphate, sorbitol or glycine; tabletting lubricant, for example magnesium stearate, talc, polyethylene glycol or silica; disintegrants for example potato starch, or acceptable wetting agents such as sodium lauryl sulfate. The tablets may be coated according to methods well known in normal pharmaceutical practice. Oral liquid preparations may be in the form of, for example, aqueous or oily suspensions, solutions, emulsions, syrups or elixirs, or may be presented as a dry product for reconstitution with water or other suitable vehicle before use. Such liquid preparations may contain conventional additives such as suspending agents, for example sorbitol, syrup, methyl cellulose, glucose syrup, gelatin hydrogenated edible fats; emulsifying agents, for example lecithin, sorbitan monooleate, or acacia; non-aqueous vehicles (which may include edible oils), for example almond oil, fractionated coconut oil, oily esters such as glycerine, propylene glycol, or ethyl alcohol; preservatives, for example methyl or propyl p-hydroxybenzoate or sorbic acid, and if desired conventional flavoring or coloring agents.
For topical application to the skin, the drug may be made up into a cream, lotion or ointment. Cream or ointment formulations which may be used for the drug are conventional formulations well known in the art, for example as described in standard textbooks of pharmaceutics such as the British Pharmacopoeia.
The active ingredient may also be administered parenterally in a sterile medium. Depending on the vehicle and concentration used, the drug can either be suspended or dissolved in the vehicle. Advantageously, adjuvants such as a local anaesthetic, preservative and buffering agents can be dissolved in the vehicle.
It will be understood that the specific dose level for any particular patient will depend upon a variety of factors including the activity of the specific compound employed, the age, body weight, general health, sex, diet, time of administration, route of administration, rate of excretion, drug combination and the severity of the particular disease undergoing therapy.
The following Examples describe the preparation of embodiments of the invention and illustrate their antiproliferative activity. The following abbreviations have been used in the examples
DCMxe2x80x94Dichloromethane
DMFxe2x80x94N,N-Dimethylformamide
HOBTxe2x80x941-Hydroxybenzotriazole
WSCDIxe2x80x94N-(3-Dimethylaminopropyl)-Nxe2x80x2-ethylcarbodiimide hydrochloride
HClxe2x80x94-Hydrochloric acid
THFxe2x80x94Tetrahydrofuran
EtOHxe2x80x94Ethanol
pTsOHxe2x80x94para-Toluene sulfonic acid
Bzl-Benzyl